The present invention relates to liquid detergents containing a surfactant system which is free of Linear alkyl benzene sulfonate surfactants (LAS), said liquid detergent having optimum greasy stain removal performance.
The recent trend towards partial or total replacement of Linear alkyl benzene sulfonate surfactants (LAS) has urged the detergent formulators to rebalance their formulations with different surfactants.
There is thus a standing desire for performance and flexibility reasons to make available a surfactant system capable of providing optimum detergency performance which is equivalent to that of LAS-containing detergents.
The above objective has been met by a surfactant system comprising anionic surfactants selected from the group consisting of alkyl alkoxylated sulfates and alkyl sulfates, said surfactant system further comprising a cosurfactant selected from the group of quaternary ammonium surfactants.
It has been surprisingly found that detergent compositions containing said surfactant system exhibit detergency performance equivalent to that of LAS-containing detergents.
In addition, it was found that the liquid detergent compositions containing the selected quaternary ammonium surfactants of the present invention, provide excellent greasy stain removal performance without detriment to the suds characteristics of the compositions. This finding allows to reduce the level of suds suppressing agents, thereby facilitating the formulation of concentrated liquid detergents.
Quaternary ammonium surfactants are described in the art. The properties of these surfactants are very strongly influenced by the type of substituent. Chain length, degree of saturation, branching or the presence and number of hydroxylic or ethoxy groups mainly determine the properties of the surfactant. Whereas typical textile-conditioning actions are performed by cationic surfactants with two long alkyl chains, cationic surfactants with only one long alkyl chain have been reported to improve the detergency performance in laundry detergents. EP-A-224 describes liquid built laundry detergent compositions comprising a general class of quaternary ammonium surfactants. Decyltrimethyl ammonium chloride is described. EP 8142 describes a liquid builder-free heavy duty detergent comprising a quaternary ammonium compound of a general formula. Octyldihydroxyethylmethyl ammonium halides are described.
For optimum grease detergency performance, however, these compositions of the prior art require high level of cationic surfactant. These high levels of cationic surfactants in turn, generate excessive foaming, thereby raising problems of automatic washing machine compatibility. If, on the other hand, the cationic surfactant is reduced at a level at which foam regulation is no longer a problem, the beneficial grease detergency characteristics of quaternary compounds are diminished.
In contrast, the surfactant system of the present invention provides optimum grease and oil removal performance, thereby not adversely affecting the suds characteristic of the detergent compositions formulated therewith.
In addition, it has been found that liquid detergent compositions formulated with said surfactant system are extremely useful when the liquid detergent compositions are in direct contact with the fabrics such as during pretreatment.